1. Technical Field
This disclosure is generally related to programmable transmitters. More specifically, this disclosure is related to a highly flexible programmable transmitter for a high-speed serial-interface.
2. Related Art
Modern communication systems use a number of high-speed communication standards which impose stringent requirements on the behavior of transmitters and receivers. Furthermore, the relentless miniaturization of integrated circuits has increased the amount of variability in the electrical characteristics of chips. Consequently, the operating parameters of a transmitter, such as impedance, attenuation, and equalization (e.g., pre-emphasis and de-emphasis) often need to be programmed during operation.
One approach for designing a programmable transmitter is to include a large number of transmitter legs (e.g., 64 transmitter legs), such that each transmitter leg has multiple configurations. Then, each transmitter leg can be configured to achieve the desired transmitter behavior during operation.
Due to the stringent and potentially conflicting requirements of different high-speed serial-interface standards, it is generally desirable for the transmitter design to be highly configurable. Specifically, it is desirable to ensure that the transmitter design allows each transmitter leg to be configured independently of other transmitter legs. Unfortunately, a highly flexible transmitter design can require a large amount of configuration information to be routed to the transmitter legs, which can substantially increase parasitic capacitance and/or wiring area in the circuit design.